This is a nice compalation of quotes by Srila Prabhupada on the class of devotee known as ‘ahajiya’.

“A class of so-called devotees known as prākṛta-sahajiyās sometimes display devotional symptoms to exhibit their good fortune. They are pretending, however, because these devotional features are only external. The prākṛta-sahajiyās exhibit these symptoms to advertise their so-called advancement in love of Kṛṣṇa, but instead of praising the prākṛta-sahajiyās for their symptoms of transcendental ecstasy, pure devotees do not like to associate with them. It is not advisable to equate the prākṛta-sahajiyās with pure devotees. When one is actually advanced in ecstatic love of Kṛṣṇa, he does not try to advertise himself. Instead, he endeavors more and more to render service to the Lord.” (Caitanya-caritāmṛta Antya 20.28, Purport)

“The Vaiṣṇavas are by far the greatest philosophers in the world, and the greatest among them was Śrīla Jīva Gosvāmī Prabhu, whose philosophy was again presented less than four hundred years later by Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura Mahārāja. Therefore one must know very well that Vaiṣṇava philosophers are not sentimentalists or cheap devotees like the sahajiyās. All the Vaiṣṇava ācāryas were vastly learned scholars who understood Vedānta philosophy fully, for unless one knows Vedānta philosophy he cannot be an ācārya. To be accepted as an ācārya among Indian transcendentalists who follow the Vedic principles, one must become a vastly learned scholar in Vedānta philosophy, either by studying it or hearing it.” (Caitanya-caritāmṛta Ādi 7.102, Purport)

“A class of so-called devotees known as prākṛta-sahajiyās sometimes display devotional symptoms to exhibit their good fortune. They are pretending, however, because these devotional features are only external. The prākṛta-sahajiyās exhibit these symptoms to advertise their so-called advancement in love of Kṛṣṇa, but instead of praising the prākṛta-sahajiyās for their symptoms of transcendental ecstasy, pure devotees do not like to associate with them. It is not advisable to equate the prākṛta-sahajiyās with pure devotees. When one is actually advanced in ecstatic love of Kṛṣṇa, he does not try to advertise himself. Instead, he endeavors more and more to render service to the Lord.” (Caitanya-caritāmṛta Antya 20.28, Purport)

“Sahajiyā… Sahaj means easy. Easy-going. They will smoke cigarette at the same time they will play rasa-līlā. This is sahajiyā. This is sahajiyā. They will do all nonsense; still, they will become God, imitation of God.” (Srila Prabhupada Morning Walk, Bombay, May 1, 1974)

Devotee: Srila Prabhupada, when one returns to his svarūpa, his natural form, how does…

Prabhupada: First of all, anartha-nivṛtti. You are accustomed to so many bad habits. First of all try to rectify it, then talk of svarūpa. Where is your svarūpa? Simply wasting time. A man is diseased, he’s thinking, ‘When I shall be cured I shall eat, go to this hotel, I shall eat like this.’ First of all cure, then talk of eating this and that. Svarūpa, when you are cured, that is svarūpa. So long you are not cured, what is the use of talking svarūpa? First business is cure yourself. Anartha-nivṛtti, that is anartha-nivṛtti. Then svarūpa will come. That is the bābājīs. In Vṛndāvana, you have seen? Siddha-praṇālī.

Devotee: Ah, siddha-praṇālī, siddha-deha?

Prabhupada: They are smoking and having illicit sex with one dozen women—svarūpa. Rascal. This is called sahajiyā, a rascal. Condemned. Where is your svarūpa? Don’t talk unnecessarily. First of all come to svarūpa, then talk of svarūpa. (Srila Prabhupada Conversation, New Vrindaban, June 23, 1976)

Prabhupada: Unless we are very sincere, we cannot cope with māyā. That is not possible. If you remain a servant of māyā, you cannot conquer over māyā. You must be very sincere servant of Kṛṣṇa. Then you can conquer. Mām eva ye prapadyante māyām etāṁ taranti te (BG 7.14). It is clearly said. Otherwise, you are subjected to the tricks of māyā.

Devotee: Unless one surrenders to Kṛṣṇa.

Prabhupada: Then you can get rid of māyā’s tricks. Otherwise, you may dress yourself like anything, but you are simply māyā’s servant. Bhaktivinoda Ṭhākura has sung one… Ei ota kalir chelā: ‘Here is another disciple of Kali.’ Nake tilaka galai mālā. ‘He has got tilaka on the nose and mālā, kaṇṭhī, also.’ Sahaja bhajana kache namu saṅge laiyā pare bhalo: ‘And he’s…, he has become a Vaiṣṇava by illicit sex.’ This is stated by Bhaktivinoda Ṭhākura. ‘Here is a Kali’s chelā. He has dressed like a Vaiṣṇava, but he is doing his bhajan with illicit sex.’ Sahaje bhajana kache mamu saṅge lana pare bhalo. You know? There is a class of sahajiyās?

Prabhupada: So Bhaktivinoda Ṭhākura: ‘Here is a disciple of Kali. He has tilaka and he has kaṇṭhī and he’s doing this nonsense.'” (Srila Prabhupada Lecture, Los Angeles, July 13, 1974)

Prabhupada: That will happen. Sahajiyā.

Devotee: Posing himself as a big, learned man.

Prabhupada: My Guru Mahārāja used to say, “When our men will be sahajiyā, he will be more dangerous.”

Devotee: Our own men.

Prabhupada: Bhaktisiddhānta Sarasvatī Ṭhākura, he said that “When our men will be sahajiyā, oh, they’ll be more dangerous.” So our men are becoming, some of them, sahajiyās. This very word he said, that “When our men will be sahajiyās he’ll be more dangerous.” (Srila Prabhupada Conversation, Bhuvanesvara, January 24, 1977)

“This is sahajiyā-vāda. He is thinking, ‘Oh I have become liberated. I don’t require any direction of my guru. I’m liberated.’ Then he’s rascal. Why this Gauḍīya Maṭha failed? Because they tried to become more than guru. He, before passing away, he gave all direction and never said that ‘This man should be the next ācārya.’ But these people, just after his passing away, they began to fight, who shall be ācārya. That is the failure.” (Srila Prabhupada Conversation, Bombay, August 16, 1976)

“Here in Los Angeles, we have found that there is a group of about 40 devotees who privately meet to discuss the intimate pastimes artificially thinking that they can enter into the understanding of the gopis prematurely. This will create havoc in our society, and the result will be that if this is allowed to go on, our preaching work will be greatly hampered. This premature desire to understand the lila of Krishna is due to mundane sex-life desire as we have seen amongst many of the babajis and sahajiyas in Vrindaban. Our Jagannatha das came back from Vrindaban asking me that he had heard some babaji speaking about siddha-deha and he also was listening to these babajis. So I want this immediately stopped. If it continues, this mixing with the babajis, then it will mean spoiling. In many cases, these babajis keep 2 or 3 women. Asatsanga tyagi. Their association is to be avoided and prohibited amongst all of our devotees who visit Vrindaban.” (Srila Prabhupada Letter, June 7, 1976)
“Following in the footsteps of Gopis comes in the perfectional stage. First you come to the perfectional stage, then you talk of Gopis. Going to girls and making them pregnant, then talking of Gopis, that is going on, that is nonsense. Without coming to the perfectional stage, if anyone tries to understand the Gopis he becomes a sahajiya. Gopis are not ordinary women, they are all expansions of Krishna’s pleasure potency. So when we understand Krishna, then we shall understand Gopis. We can simply follow foot prints of Gopi how they loved Krsna.” (Srila Prabhupada Letter, December 14, 1972)

“Don’t try to understand Rādhā-Kṛṣṇa very quickly. It is a very big subject. If we want to understand Rādhā-Kṛṣṇa very quickly, then there will be so many prākṛta-sahajiyās. In India there are prākṛta-sahajiyā. Just like Rādhā-Kṛṣṇa dancing. Rādhā-Kṛṣṇa has become a plaything. The painting Rādhā-Kṛṣṇa, Kṛṣṇa is kissing Rādhā, Rādhā is kissing. These are all nonsense. Rādhā-Kṛṣṇa philosophy has to be understood by the liberated person, not by the conditioned soul. So we shall await for the fortunate moment when we are liberated, then we shall understand rādhā-kṛṣṇa-praṇaya-vikṛtir. Because Kṛṣṇa and Rādhā, They are not on the material field.” (Srila Prabhupada Lecture, Montreal, August 30, 1968)